Herbicidal diphenyl n chlorophenoxyacetyl thiazone imines and a process for their preparation

ABSTRACT

2,3-DIPHENYL-N-(CHLOROPHENOXYACETYL)-THIAZONE IMINES ARE PREPARED BY REACTING S-CYANOMETHYLISOTHIOBENZANILIDE WITH A DI- OR TRI-CHLOROPHENOXYACETYL CHLORIDE, PREFERABLY IN AN INERT SOLVENT, TO FORM THE HYDROCHLORIDES OF THESE N-ACYL DERIVATIVES. NEUTRALIZATION OF THE HYDROCHLORIDES GIVES THE FREE BASES. THE COMPOUNDS ARE USEFUL AS HERBICIDES.

United States Patent Oifice 3,766,201 HERBICIDALDIPHENYL-N-(CHLOROPHENOXY- ACETYL)-THIAZONE IMINES AND A PROCESS FORTHEIR PREPARATION Elmer F. Litzinger, Louisville, Ky., assignor toAllied Chemical Corporation, New York, N.Y.

No Drawing. Original application Mar. 19, 1969, Ser. No. 808,659, nowPatent No. 3,617,248. Divided and this application Mar. 29, 1971, Ser.No. 129,210

Int. Cl. C07d 91/32 US. Cl. 260-306.8 R Claims ABSTRACT OF THEDISCLOSURE 2,3-diphenyl-N-(chlorophenoxyacetyl)-thiazone imines areprepared by reacting S-cyanomethylisothiobenzanilide with a diortri-chlorophenoxyacetyl chloride, preferably in an inert solvent, toform the hydrochlorides of these N-acyl derivatives. Neutralization ofthe hydrochlorides gives the free bases. The compounds are useful asherbicides.

This is a division of application Ser. No. 808,659, filed Mar. 19, 1969,now US. Patent 3,617,248.

BACKGROUND OF THE INVENTION The novel compounds of the instant inventionare diand trichlorophenoxyacetylthiazone imines of the formula:

GI R

wherein R is hydrogen or chlorine. These compounds are prepared byreacting S-cyanomethylisothiobenzanilide with a diortrichlorophenoxyacetyl chloride to form the hydrochlorides of thecorresponding diand trichlorophenoxy acetylthiazone imines, which arethen neutralized to give the free bases. The novel compounds are usefulas herbicides.

The sydnone-like, meso-ionic structure of the novel compounds is aresonance hybrid which exists in several ionic states and has largedipole moments.

DETAILED DESCRIPTION OF THE INVENTION Preparation of the instantcompounds is unexpectedly accomplished by reactingS-cyanomethylisothiobenzanilide with an appropriate phenoxyacetylchloride, prefer- 3,766,201 Patented Oct. 16, 1973 ably in an inertsolvent, to form the hydrochloride according to the following sequence:

Neutralization of the hydrochlorides gives the corresponding free bases.Approximately equimolar amounts of the two substrates is normally used,although an excess of either might be used to achieve a higher yieldwith respect to the other.

The reaction can be conducted without use of an inert solvent althoughit is more convenient to use solvent. Without solvent, the reaction isconducted above the melting point of S-cyanomethylisothiobenzanilide,i.e., above about 69 C. and the phenoxyacetyl chloride is added to themolten S-cyanomethylisothiobenzanilide. Preferably, the reaction will beconducted at a temperature within the range of about 69 to 150 C., andmore preferably to C. Reaction times as short as about one hour or lesshave been found to be adequate, although longer reaction times may beused if desired. Atmospheric pressure is normally used for the reaction,although subatmospheric or superatmospheric conditions might beemployed.

The reaction is preferably conducted in an inert solvent such as benzeneand toluene. Considerations regarding reaction temperature, time andpressure, specified hereinbefore are appropriate for this purpose,although somewhat lower temperatures might be used if desired.

It has been found that it is preferable that the reaction be conductedin the absence of base in order to obtain the desired hydrochloride ofthe product, i.e., at a pH less than about 7.0. Presence of a base oracid acceptor in the reaction medium results in a competing reactionproduct. Preferably, solvent is separated from the producthydrochloride, and the hydrochloride is neutralized with an alkali, suchas sodium bicarbonate in aqueous solution, to form the free base.

Substrate materials are readily available by procedures taught in theprior art. For example, S-cyanomethylisothiobenzanilide might beprepared by the following procedure: About 3.6 parts (by weight) oftricthylamine is added to a solution of 5 parts thiobenzanilide and 1.8parts chloroacetonitrile in about 22 parts of benzene, and the mixtureis heated at 50 C. for nine hours. The mixture is then allowed to standovernight and the separated triethylamine hydrochloride is filtered off.The filtrate is evaporated to dryness under reduced pressure, and theresidual crystals are collected. Recrystallization from ether-petroleumether gives 3 parts of S-cyanomethylisothiobenzanilide as colorlessneedles having melting point of 68 to 69 C.

The instant compounds have been found to be unexpectedly effectiveherbicides in that they are very harmful to plants normally consideredundesirable, such as rape and broadleafed weeds, while being harmlesstoward such plants as corn and wheat,2,3-diphenyl-N-(2,4-dichlorophenoxyacetyl)-thiazone imine is thepreferred compound for this purpose.

Normally, the instant compounds will be used as the active ingredient inan herbicidal composition, although they might also be used without acarrier. Various diluents and carriers may be employed and the percentof active ingredient may be varied. Although compositions with less thanabout 0.5 percent by weight of active ingredient may be used, it ispreferable to use compositions containing at least about 1.0 percent ofactive ingredient because otherwise the amount of carrier becomesexcessively large. Activity increases with the concentration of activeingredient, which may be 10, 50, 95 percent or even higher.

The amount of composition which is applied for effective herbicidalaction is dependent upon considerations such as the type of undesirableplant to be killed, the density of undesirable plants, and soil andclimatic conditions. Usually, sufficient composition will be applied toprovide about 8 to 16 pounds of active ingredient per acre.

The instant herbicidal compositions may be in the form of a solution,with the solvent being selected from acetone, benzene, and the like.These solutions can be applied to the plants in a direct manner such asby spraying, sprinkling, drenching, etc. Water suspensions can also beapplied in this manner, with dispersing and emulsifying agents such assodium alkyl sulfates and sulfonates and the like.

Application can also be achieved by dusting a powder in which the activeingredient is dispersed. Suitable carriers include finely powderedmaterial such as clays, fullers earth, talc, etc.

The instant compounds may constitute the sole active ingredient in theherbicidal compositions, but they might be effectively used incombination with other active ingredients, such as other herbicides,insecticides and other plant treating agents.

The following examples are provided to more fully illustrate the instantinvention.

EXAMPLE I 2,3-diphenyl-N-(2,4-dichlorophenoxyacetyl)- thiazone imine 1About 6 grams of 2,4-dichlorophenoxyacetyl chloride and 6.31 grams ofS-cyanomethylisothiobenzanilide were placed in a flask containing 44grams of dry benzene. The flask was attached to a condenser connected toa drying tube, and the reaction mixture was heated to about 80 C. on asteam bath. Within two minutes, solids began forming in the mixture. Thereaction mixture was heated at about 80 C. for one hour then cooled toabout room temperature. The solids were separated from the reactionmixture and washed with diethyl ether. The solids were then dissolved inwater and the solution was mixed with a saturated solution of NaHCO Thedesired product precipitated from the solution and was separated bytfiltration. Yield: 9.3 grams; melting point 184 to 185 C. Structure wasconfirmed by infrared analysis.

EXAMPLE ]I The procedure of Example I is repeated wherein an equivalentamount of appropriate phenoxyacetyl chloride is used to afford thefollowing products:

2,1i-diphenyl-N-(2,S-dichlorophenoxyacetyl)-thiazone 2,?icligfienyl-N-(2,6-dichlorophenoxyacetyl)-thiazone ZJI- E iEEenyI-N- (3,5 -dichlorophenoxyacetyl) -thiazone 2, Fi iiSZenyl-N- (2,4,5-trichlorophenoxyacetyl) thiazone lgiiiglienyl-N-(2,4,6-trichlorophenoxyacetyl)-thiazone 2, iigiglienyl-N- (3,4,5-trichlorophenoxyacetyl) -thiazone 4 EXAMPLE 111 Herbicidal activity Thefollowing crop species and weed species were planted in metal flats (12x 8.5 x 4 inches) in greenhouse potting soil containing one-third mixedclay and sand, one-third mushroom soil, and one-third peat moss. The pHof the soil was 6.8 to 7.2.

Crop species:

Corn, Zea mays, Hybrid U.S. 13 Wheat, T riticum vulgare, variety ThorneSoybean, Soja wax, variety Wilson Weed species: Ryegrass Rapc Each flatreceived a volume of spray equal to gallons per acre of an acetonesolution of 2,3-diphenyl-N- (2,4-dichlorophenoxyacetyl)-thiazone imine.The concentration of the solution was adjusted to provide application of8 pounds of active ingredient per acre. Immediately after spraying, thetest flats were placed in aluminum trays and were irrigated until thesurface of the soil in the flat was uniformly moist (at field capacity).Additional subirrigation was provided as needed to maintain moisture. Nosurface irrigation was applied.

The flats were sprayed within one day after seeding in preemergencetests, and 8 to 10 days after seeding in the postemergence tests.Results were observed 14 days after spraying.

The effect of the herbicide was evaluated in terms of the injury ratingindex scale, ranging from 0 to 10 as follows:

0-No apparent injury 1, 2, 3Slight injury 4, 5, 6Moderate injury 7, 8,9Severe injury (plants will die) 10--Plants were dead An injury ratingof 3 is the maximum tolerated for The aforementioned examples areprovided for illustrative purposes only and are not to be construed aslimiting the scope of the instant invention, which is defined by theappended claims.

I claim:

1. Compounds of the formula:

G: b R

wherein R is hydrogen or chlorine.

2. Compounds of claim 1 wherein R is hydrogen.

3. The compound of claim 1 wherein said compound is2,3-diphenyl-N-(2,4-dichlorophenoxyacetyl) thiazone imine.

4. A process for the preparation of a herbicidal compound of theformula:

5 6 wherein R is hydrogen or chlorine, which comprises: in aqueoussolution to precipitate the herbicidal (a) reacting achlorophenoxyacetyl chloride of the compound as a free base.

formula 5. The process of claim 4 wherein the herbicidal compound is2,3-diphenyl-N-(2,4 dichlorophenoxyacetyl)- Cl 01 0 5 thiazone imine.

l OCHzCl References Cited R UNITED STATES PATENTS wherein R is asaforesaid, with S-cyanomethyliso- 3617248 11/1971 Lltzmger 260 306'7thiobenzanilide in an inert solvent at a temperal0 FOREIGN PATENTS tureof about 69 to 150 C. and at a pH less 534 4/1966 Japan 7 than 7 to givea hydrochloride of said herbicidal pound. RICHARD J. GALLAGHER, PrimaryExaminer (b) separating the hydrochloride from the inert solvent; and 15U.S. Cl. X.R.

(c) neutralizing the hydrochloride with an alkali 260306.7

